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Tensile Deformation, Toughness and Crack Propagation Studies of Alloy 617 UNLV Retrospective Theses & Dissertations 1-1-2007 Tensile deformation, toughness and crack propagation studies of alloy 617 Vikram Marthandam University of Nevada, Las Vegas Follow this and additional works at: https://digitalscholarship.unlv.edu/rtds Repository Citation Marthandam, Vikram, "Tensile deformation, toughness and crack propagation studies of alloy 617" (2007). UNLV Retrospective Theses & Dissertations. 2792. http://dx.doi.org/10.25669/5x53-uv5y This Dissertation is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Dissertation in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/or on the work itself. This Dissertation has been accepted for inclusion in UNLV Retrospective Theses & Dissertations by an authorized administrator of Digital Scholarship@UNLV. For more information, please contact [email protected]. TENSILE DEFORMATION, TOUGHNESS AND CRACK PROPAGATION STUDIES OF ALLOY 617 by Vikram Marthandam Bachelor of Engineering in Mechanical Engineering University of Madras, India Master of Science in Mechanical Engineering, 2004 University of Nevada, Las Vegas, Las Vegas, NV 89154 A dissertation submitted in partial fulfillment of the requirements for the Doctor of Philosophy Degree in Mechanical Engineering Department of Mechanical Engineering Howard R. Hughes College of Engineering Graduate College University of Nevada, Las Vegas May 2008 UMI Number: 3319132 INFORMATION TO USERS The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, If unauthorized copyright material had to be removed, a note will indicate the deletion. UMI UMI Microform 3319132 Copyright 2008 by ProQuest LLC. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest LLC 789 E. Eisenhower Parkway PC Box 1346 Ann Arbor, Ml 48106-1346 Dissertation Approval The Graduate College University of Nevada, Las Vegas A p r il 1 0 20 08 The Dissertation prepared by Vikram Marthandam Entitled Tensile Deformation, Toughness and Crack Propagation Studies of Alloy 617 _____________ _____________ is approved in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mechanical Engineering Examination Committee Chair Dean of the Graduate College Examination Committee Member Examination Committee Member Examination Committee Member Graduate College Faculty Representative 11 ABSTRACT Tensile Deformation, Toughness and Crack Propagation Studies of Alloy 617 By Vikram Marthandam Dr. Ajit K. Roy, Examination Committee Chair Professor of Mechanical Engineering University of Nevada, Las Vegas Austenitic nickel-base Alloy 617 has been tested under tensile loading at temperatures relevant to both the Nuclear Hydrogen Initiative and the Next Generation Nuclear Plant programs of the U.S. Department of Energy. Two important metallurgical phenomena, namely dynamic strain aging (DSA) and yield strength anomaly (YSA), have been identified based on the resultant data. DSA was characterized by reduced plastic strain and serrations in the engineering stress versus engineering strain diagrams. YSA was manifested by enhanced yield strength at relatively higher temperatures. A mechanistic understanding of DSA and Y SA phenomena has been developed based on the estimation of dislocation density, activation energy, work-hardening index and precipitate morphology, where applicable. Stress-intensity-factor and crack-growth-rates of this alloy have been evaluated with and without the presence of an acidic solution at different temperatures using fracture-mechanics-based principles. Fractographic evaluations of all tested specimens have also been performed to characterize the extent and morphology of failures resulting from different modes of loading. Ill TABLE OF CONTENTS ABSTRACT................................................................................................................................. iii LIST OF TABLES........................................................................................................................vi LIST OF FIGURES........................................................................................................... vii ACKNOWLEDGEMENTS..........................................................................................................x CHAPTER I INTRODUCTION.................................................................................................I CHAPTER 2 TEST MATERIAL AND SPECIMENS AND ENVIRONMENT ...............9 2.1 Test M aterial..................................................................................................................... 9 2.2 Test Specimens ............................................................................................................... 11 2.2.1 Tensile Specimen ..................................................................................................12 2.2.2 Compact-Tension Specimens .............................................................................. 13 2.2.3 DCB Specimen ...................................................................................................... 16 2.3 Test Environment ............................................................................................................19 CHAPTER 3 EXPERIMENTAL PROCEDURES.................................................................21 3.1 Tensile Testing ................................................................................................................22 3.2 Parameters Related to Tensile Deformation ...............................................................25 3.2.1 Dislocation Density Calculation ........................................................................ 26 3.2.2 Activation Energy Calculation ............................................................................28 3.2.3 Computation of Strain Hardening Exponent .....................................................31 3.3 Fracture Toughness Measurement ............................................................................... 33 3.4 Crack Propagation Study .............................................................................................. 35 3.5 s e e Testing using DCB Specimens ............................................................................37 3.6 Metallographic Evaluations ..........................................................................................39 3.7 Fractographic Evaluations .............................................................................40 3.8 Transmission Electron Microscopic Evaluations .......................................................41 3.8.1 TEM Sample Preparation .................................................................................... 42 3.9 Phase Characterization ...................................................................................................44 CHAPTER 4 RESULTS.............................................................................................................46 4.1 Microstructural Evaluations ..........................................................................................46 4.2 Tensile Properties Evaluation .......................................................................................48 4.2.1 Dislocation Density Calculation .........................................................................54 4.2.2 Activation Energy Calculation ............................................................................58 4.2.3 Estimation of Work-Hardening Index ...............................................................64 IV 4.2.4 Characterization of YSA ................................................................................... 66 4.3 Kic Evaluation ................................................................................................................74 4.4 Determination of Crack-Growth-Rate ........................................................................ 75 4.5 DCB Test Results............................................................................................................84 4.6 Fractographic Evaluations ............................................................................................ 85 CHAPTER 5 DISCUSSION.................................................................................................... 103 CHAPTER 6 SUMMARY AND CONCLUSIONS.............................................................107 CHAPTER 7 SUGGESTED FUTURE WORK................................................................... 110 APPENDIX A INSTRON TESTING DATA........................................................................111 APPENDIX B RESULTS OF K,c TESTING.......................................................................139 APPENDIX C RESULTS OF CGR TESTING.....................................................................140 APPENDIX D SCANNING ELECTRON MICROGRAPHS
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